A vertical disc of diameter 10 cm makes 20 revolutions per second about a horizontal axis passing through its centre. A uniform magnetic field 10⁻¹ ~T acts perpendicular to the plane of the disc. If the potential difference between its centre and rim is found to be x 10^ -p Volt, then find the ratio of x / p .

Step-by-step solution

As we know, disc is equivalent to a rod of length r . Divide disc into rods, each rod can be replaced by a battery and these batteries are would be paralial in arrangement. According to the question, radius of disc, r= 10 2 =5 ~cm =0.05 ~m Angular velocity, =20 2 =40 rad / s Magnetic field, B=10⁻¹ ~T The emf of a disc is given as e= 1 2 B r^2= 1 2 (10⁻¹ )(40 )(0.05)^2 V₀-V_A=1.57 10⁻² ~V = 2 10⁻² ~V = x 10^ -p ~V (given) x p = 2 2 =1